JPS61216371A - Mold type magnetic resistance element - Google Patents

Abstract

PURPOSE:To enable the magnetic resistance pattern surface of a magnetic resistance element and the magnetic medium surface on a moving object to approach each other as close as necessary by a method wherein the necessary part of the magnetic resistance element chip is protected with a high molecular resin film. CONSTITUTION:A mold type magnetic resistance element S is formed in such a manner that a magnetic resistance element chip S is fixed on a lead frame supporter 8 and a mold of thermosetting resin 9 is applied. In this mold type magnetic resistance element S, the first buffer layer made of molecular resin 6 is formed on the magnetic resistance element chip S and the second buffer layer made of adhesive high polymer resin is provided between the lead frame supporter 8 and the magnetic resistance element S. Also, the mold of the thermosetting resin 9 is so applied as to have the same height as the surface of the magnetic resistance element chip to expose the surface of the magnetic resistance element S. The magnetic resistance pattern surface and the magnetic medium surface on a moving object can approach each other as close as necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a molded magnetoresistive element used in a wide range of applications such as detecting the rotational speed of a rotating body, detecting the position of a moving body, and detecting the presence or absence of a low magnetic field.

SUMMARY OF THE INVENTION The present invention relates to a molded magnetoresistive element in which a magnetoresistive element chip on which a magnetic thin film pattern is formed is fixed on a lead frame support and covered with a thermosetting resin.

a first buffer layer made of a polymer resin formed on the magnetoresistive element chip;

A second buffer layer made of an adhesive polymer resin is interposed between the lead frame support and the magnetoresistive element, and is made of a thermosetting resin at the same height as the magnetoresistive element chip surface. It has an exterior.

This has the effect that resolution can be improved by bringing the distance to the magnetic medium closer.

Prior art A conventional molded magnetoresistive element is formed on a smooth substrate such as a glass substrate, a silicon substrate, or a glazed ceramic substrate.
It has a structure in which a predetermined magnetic thin film pattern is formed using a ferromagnetic material such as nickel-iron or nickel-cobalt, and lead wires and exterior packaging are performed. The exterior can be in various different exterior states depending on the connection method of the lead wires.

When connecting lead wires using the soldering method, a magnetic thin film and an electrode thin film are formed on a glass substrate or glazed alumina substrate by vacuum evaporation or sputtering, a magnetic film pattern is formed using microfabrication technology, and a connecting electrode is formed. The part and the lead terminal are connected by high-temperature solder. The exterior is then applied using a powder resin coating method using a powder epoxy range.

When a connection by the wire bonding method is used, the structure is as shown in the cross-sectional view of FIG. 2(A) and the partially broken perspective view of FIG. 2(B). That is, as shown in FIG. 1C, first, a SiO□ film 11 is formed on a silicon substrate 10 by sputtering, a nickel-iron thin film and a gold thin film are formed thereon by vacuum evaporation or sputtering, and then photo-coated. Nickel-iron thin film pattern 12 and connection gold electrode made using lithography technology and microfabrication technology! 5 by the zero-order sputtering method to form 3.
IntlI 114 is adhered to the entire element, and only the upper part of the connection gold electrode 13 is removed to complete the magnetoresistive element chip S. Then, after fixing the magnetoresistive element chip S onto the lead frame 1B with a thermosetting adhesive,
As shown in A) and (B), the lead frame 16 and the connection gold electrode 13 are connected with the bonding wire 15. Thereafter, a suitable buffer coating resin is applied, and finally, transfer molding is performed using thermosetting resin 17, and unnecessary portions of the lead frame are removed to complete the molded magnetoresistive element.

When a molded magnetoresistive element is used to detect the angle of a rotating object or the position of a moving object, a magnetoresistive element in which a bridge circuit is formed by arranging multiple magnetic thin film resistance patterns in parallel, which is usually called a blind pattern, is used. used. A plurality of magnets magnetized at the same pitch as the pitch of the magnetic thin film resistance pattern of the magnetoresistive element are arranged on the rotating body or the moving body side, and the magnetic thin film resistance pattern of the magnetoresistive element and the moving body side are arranged. The magnetic thin film resistor pattern is opposed to the magnetic medium, and the resistance change of the magnetic thin film resistor pattern is detected depending on the relative positional relationship.

Therefore, in order to obtain a sufficient detection output, the magnetoresistive element should be placed as close as possible to the magnetic medium on the moving object side,
It is necessary to set the distance to be approximately the same as the magnetization pitch. The tIm pitch is usually less than 0.3, and sometimes less than 0.11. However, conventional molded magnetoresistive elements are made of thermosetting resin 17
Because of the large thickness, the 81-magnetic resistance element cannot be brought sufficiently close to the surface of the magnetic medium on the movable body side.

Problems to be Solved by the Invention The present invention solves the above-mentioned conventional drawbacks and provides a structure in which the distance between the magnetoresistive element and the magnetic medium surface of the moving body can be reduced.

Means for Solving the Problems The molded magnetoresistive element of the present invention is a molded magnetoresistive element in which a magnetoresistive element chip on which a magnetic thin film pattern is formed is defined on a lead frame support, and the molded magnetoresistive element is covered with a thermosetting resin. In Motoko.

a first buffer layer made of a polymer resin formed on the magnetoresistive element chip;

A second buffer layer made of an adhesive polymer resin is interposed between the lead frame support and the magnetoresistive element, and is made of a thermosetting resin at the same height as the magnetoresistive element chip surface. The problem is solved by exposing the magnetoresistive element surface by using an exterior structure.

Embodiments of the Invention Next, the present invention will be described in detail with reference to the drawings.

FIGS. 1(A), 1(B), and 1(C) are a sectional view, a partially exploded perspective view, and a detailed sectional view of the main parts, respectively, showing one embodiment of the present invention. That is, first, as shown in the same figure (C), 5i
02112 was formed to form an insulating film, a nickel-iron thin film was formed on it by vacuum evaporation or sputtering, and then a gold thin film was formed in the same vacuum, using photolithography technology and Wk fine processing technology. A nickel-iron thin film pattern 3 and a gold thin film pattern are formed. followed by 5i
02 film 5 is formed by sputtering method.

The gold electrode 4 for connection is formed using microfabrication technology. Furthermore, a protective film made of a polymer resin film 6 is formed on top of the first film.
as a buffer layer, and the magnetoresistive element chip S shown in the same figure (C)
is completed.

The magnetoresistive element chip S is placed on a second lead frame 8.
Flexible type silicone bonding as a buffer layer 1
It is fixed through the agent. after that.

A bonding wire 7 is used to connect the lead frame 8 and the connection gold electrode 4, and a thermosetting resin 9 is used to bond the upper surface of the magnetoresistive element chip S as shown in FIGS. Necessary parts are exposed and transfer molding is performed on other parts. That is, the height of the thermosetting resin 9 is the same as the height of the magnetoresistive element S, and the surface of the thermosetting resin 9 is It forms the same plane as the surface of the magnetoresistive element chip S.

In this embodiment, the entire molded magnetoresistive element is protected by thermosetting resin 9, and the magnetoresistive element chip S
The portion of the upper surface that contacts the moving body is protected by the polymer resin film 6 as the first buffer layer. The 5i02 film 5 and the polymer resin film 6 can be formed to an arbitrary thickness (for example, 50 mm or less), and can be formed on the magnetic resistance pattern surface formed on the silicon substrate and the magnetic medium surface on the moving body. It is possible to bring them close to each other at the required distance. Therefore, there is an effect that sufficient sensitivity and resolution can be obtained. Further, since the upper and lower surfaces of the magnetoresistive element chip S have the first and second buffer layers (silicon adhesive), respectively, damage to the element itself by the mold during molding is prevented. In addition, since the lead frame method is adopted, automation is easier than conventional soldering methods, suitable for mass production, and can be provided at low cost.

Effects of the Invention As described above, in the present invention, the necessary portions of the magnetoresistive element chip are protected by a polymer resin film, so that the magnetoresistive pattern surface of the magnetoresistive element and the magnetic medium on the moving body are protected. It is possible to approach the plane as close as necessary. Therefore, there is an effect that sufficient sensitivity and resolution can be obtained.

[Brief explanation of the drawing]

FIGS. 1(A), CB), and (C) are a sectional view, a partially exploded perspective view, and a sectional view of a main part, respectively, showing an embodiment of the present invention, and FIGS. 2(A) and 2(B). (C) is a sectional view, a partially exploded perspective view, and a sectional view of a main part, respectively, showing an example of a conventional molded magnetoresistive element. In the figure, 1: silicon substrate, 2: SiO□ film, 3:
Nickel-iron thin film pattern, 4: Gold electrode for connection, 5:5
TO2 film, 6: polymer resin film, 7: bonding wire, 8: lead frame, 9: thermosetting resin, 10: silicon substrate, 11: Si OL film, 12: nickel-iron thin film pattern, 13: gold for connection Electrode, 14:5i02
film, 15: bonding wire, 18: lead frame, 17: thermosetting resin, S: magnetoresistive element chip.

Claims (1)

[Scope of Claim] A molded magnetoresistive element in which a magnetoresistive element chip on which a magnetic thin film pattern is formed is fixed on a lead frame support and covered with a thermosetting resin, comprising: a first buffer layer made of a thermosetting resin; and a second buffer layer made of an adhesive polymer resin interposed between the lead frame support and the magnetoresistive element; and a second buffer layer made of a thermosetting resin. 1. A molded magnetoresistive element, characterized in that an exterior is provided at the same height as the chip surface of the magnetoresistive element.